Improvement in speed-indicator for vessels



".PEIERS. PHOWUTHQGRAPNER. WASHINGTON. D C.

mui/tell y armenie team Paten.; No'. 92,078, dates .ma 29, 1869.

IMPROVEMENT IN' SPEED-INDICATOR FOR VESSELS.

The Schedule referred to in these Letters Patent and making part of the same.

p To all 'whom Muay conce/rn:v

Beit known thatI, HENRY METcALF, of Washington, in the county of Washington, and in the District of Columbia, 'have invented certain new and useful Improvements in Naval and Current Velocimeter; and do hereby declare that the following is a full, clear, and exact description thereof, reference being had to the .accompanying drawings, and to the letters of reference marked thereon, making apart of this specification.

The nature of'my invention consists in the construction of a simple device, by means of which the speed of vessels can at once, andaccurately, be ascertained.

The accompanying drawing represents a side elevation of my invention.

My velociniet'er consists of three parts, a motor, an

indicator, and a compensator, with the necessary connections between the parts.

The motor or force-pipe consists 0f a tube, A, which passes `through the bottom of the vessel amidships, tangent to the vlvertical plane of4 right section through the centre of `gravity,1and tangent to the keel, hasone or more rectangular turns to the front, presenting thus one or more circular mouths, whose planes are at right angles to the vessels axis.

The compensatory -tube B is in all respects, in length/ above the water-line, and diameter of bore, &c., ex'- actly the same as the force-tube, only differing in its lower extremity, which is cut flush with the vessels bottom, or with the plane of its mouth or months, inclined slightly upward and to the rear.

These two pipes are placed in contact, the compensator directly behind the force-pipe, and lead up to any convenient place of observation.

Attheir upper ends, they each have a very flexible rubber` tube, U, about a foot in length, attached to them, which ,only servesto maintain the connection between them and the indicator l), which consists of la glass tube bent double.

On thebranch connected to the force-pipe there is a bulbi'ormed, which is to be halt'illed with mercury.

This indicator is suspended from asmall hook, placed between the upper ends of the pipes, by a wire, or from apoint below on gimbals, which allow it to oscillate freely in any direction, like a pendulum.

Between the branches of the indicator there is placed an adjustable scale, E, so that its zero shall be on a llevel with the mercurys surface in both branches.

AThe manner ot' using and operating the parts is .as follows:-

Suppose only the force-pipe and the gauge to be used. Start the vessel forward, and from the shape ot' the mouth of the pipe., a column ofwater is driven up and maintained in it, bringing, trom the compression ofthe air within, a pressure per square inch on the mercury in the b nlb equal to that which it sustaiusfrom the .inertia and friction ot the particles of water below7 which pressure, for a given speed, being constant, would maintain the mercury at an equally constant altitude.

This simple plan would do v ery well, were the line of flotation invariableor never changed permanently from loss or addition of cargo, ortemporarily'from the rolling and pitching at sea.

It is to obviate the fluctuation due to this change of draught that I introduce my second compensatoryA tube, which brings uponthe mercury, in thebranch connected with it, just .as great a pressure from any such cause as the force-pipe.

Thus the pressure due to the velocity is the only one capable of changing the level of the mercury,

. If, however, a more delicate fluid should be required, i

giving a greater range for the same difference of speed, the mercury could be lightened, as to its specific gravity, by amalgamation with tin, zinc, or the alkalinev metalloids. s

Were a larger scale than one thus obtained required, a saturated solution of some salt might be used to diminish. the height to. which water would go (18T at sixteen knots) if it were'left at its natural density.

From the position of the pipes moutlnbeing so sheltered by the keel, it would not be injured if the ,'vessel should touch bottom, and being 'so far. under water, would not be liable to being cloggedby doating sealweeds. But even in this case, the action ot' the gauge depending on a pressure, and not a flow, unless thepipe were hermetically sealed,so asto prevent an indication of variation in velocity, the obstacle to an Y ascent ot' the column of water would equally oppose an outward How, and its attendant diminished pressure.

The case being similar to the apparent paradox o f twov largely unequal volumes -of liquid sustaining each other at the same level when communication between them is made.

I The scale being graduated according to'ln'autical miles, (a matter easily done, since the pressure and height would vary as the square of the velocity,) a simple .inspection would be all that wo'uldbe necessary to determine the, rate. v

Should the aperture be closed by barnacles, of the probability' ot' which I cannot judge, they could be removed by unscrewing a section of pipe above the water-line, and then by introducing and pushing down a jointed tool, half-inch gas-pipe being used. I do not l,think that .the most complete instrument would cost, in material, over $15.

It might be put on ships afioat thus: Bore, at the required places, through the vessels bottom to the copper, a small hole, say of one inch diameter. Around this, and reaching above the water-line, have a two or three-inch pipe, with a. flanged month and rubber washer, making, when screwed down to the Vessels bottom timbers, a water-tight joint atits base'. Then, with a long auger, cut through the copper. Drop through the hole a line, which grapple for outside, and to theend of which fasten an iron rod, 1, connected with a tight caisson, 2, (with 'a slide-valveopened by a line passing over the side,) cut to partially fit the bottom, and, for exclusion, provided with a hollow anv nular rubber washer, 3. Draw the rod through the hole by means of the screw cut on its end. Draw the caisson snugly against the bottom. Pumpout the `water-the external pressure-will keep it in position.

Remove the rod at the shoulder 4. flanged pipe.

Take away the Put in place the force and compensating-pipes, which, to prevent galvanic action, should have copper ends and lining. Tamp the hole made force-pipe A, parallel with the tube B, and with its mouth at rightaugles `with the axis of the vessel, substantially as set forth. v

2. The combination and arrangement of' the indicating-scale D E with the tube B and pipe A, and

connected by the flexible tubes C O, all substantially' as specified.

In testimony that l claim the foregoing, I have hereunto set my hand, this 11th day of May, 1869. HENRY METOALF. Witnesses:

F. A. LEHMANN, `NrnLsoN JOHNSON. 

